Sander Backing pad Abrasive Mount Type Adhesive-Backed Abrasive Mounting Quick Change System Not Applicable Connector Size 5/16 In.-24 Connector Type Threaded Hole Backup Pad Shape Round Device Material Rubber Density Medium Maximum Operating Speed 10 000 RPM Number of Vacuum Holes Non-Vacuum Color Black Overall Length 8 in Overall Width 8 in Overall Diameter 8 in Overall Thickness Not Applicable Product Type Disc Backup Pad Compatible with Manufacturer Model Number 311A